1. Field of the Invention
The present invention relates generally to semiconductor devices and methods of fabricating the same and particularly to semiconductor devices that employ a borazine-based compound for an interlayer insulation film to achieve enhanced contact between the insulation film and an adjacent layer, such as an interconnection layer, a conductor diffusion preventing layer and the like that are adjacent to the insulation film, and methods of fabricating the same.
2. Description of the Background Art
In recent years, as semiconductor integrated circuits are increasingly highly integrated, the circuits have interconnections spaced narrower and increasing in parasitic capacitance therebetween. Semiconductor integrated circuits that require foremost fast operation are required to avoid signal delay and accordingly it is necessary to reduce such parasitic capacitance between interconnections. Furthermore, in order to avoid signal delay, it is also necessary to simultaneously reduce a material for interconnection in resistance. For semiconductor integrated circuits, aluminum and the like have been employed. Recently, copper is increasingly used as it has a small value in resistance. Furthermore, parasitic capacitance between interconnections is reduced by a method reducing an insulation film between interconnections in relative dielectric constant.
However, for example, a carbon containing silicon oxide film that is employed in the 90 nm generation is a film having a relative dielectric constant of around 2.8, and a hardness of 1.8 GPa and a Young's modulus of 14 GPa, which are significantly smaller than a hardness of 10 GPa and a Young's modulus of 80 GPa of a conventionally employed silicon oxide film and it has been pointed out that it has disadvantageous, smaller mechanical strength. As such, in a chemical mechanical polishing (CMP) step in forming a metal interconnection, a wire bonding step in assembly, and the like, there are concerns that the film may peel off, cracks and the like.
Furthermore, a film having a relative dielectric constant of around 2.2 that is expected to be applied in the 65 nm and 45 nm generations is expected to have further smaller values in hardness and Young's modulus of 0.6 GPa and 6 GPa, respectively.
Furthermore, while copper is increasingly used for a material for interconnection to avoid signal delay, as described above, there is a concern, as semiconductor devices are increasingly micro-fabricated, that the electric charge stored in an interconnection increases in density, and a local current and thermal stress concentration cause electromigration and stress migration serving as a cause of impaired reliability of the interconnection. Accordingly it is necessary to provide enhanced contact between an a material for insulation and that for interconnection.
Japanese Patent Laying-Open No. 2004-186649 discloses a method of forming an interlayer insulation film including a B—C—N bond to allow a film to be deposited with a small dielectric constant and high mechanical strength, and high bonding strength. The film is deposited by chemical vapor deposition using as a source material a compound having a borazine skeleton shown in the following chemical formula (1):
alone or in combination. In the chemical formula, X1, X2 and X3 may be identical or different and are each a hydrogen atom, the amino group or the alkyl, alkenyl, alkynyl, monoalkylamino or dialkylamino group having a carbon number of 1-4 and Y1, Y2 and Y3 may be identical or different and are each a hydrogen atom, the alkyl, alkenyl or alkynyl group having a carbon number of 1-4 or the trialkylsilyl group having a carbon number of 3-12, and X1, X2 and X3 and Y1, Y2 and Y3 are not all hydrogen atoms. A hardness and a Young's modulus having as high values as 2.0 GPa and 40 GPa, respectively can be achieved.